The present invention relates to systems and instruments for monitoring and analyzing video sources.
Video test instruments and systems are able to monitor and analyze video sources in an ever increasing variety of both analog and digital formats. Examples of analog formats include NTSC, PAL, and SECAM. Digital formats include both standard definition (SD) and high definition formats (HD). Examples of digital formats include CCIR601, and various MPEG formats, including H.264. Digital video may be transmitted for example using a serial digital interface (SDI).
In addition to monitoring video sources and analyzing them to provide a variety of measurements, some video test instruments and systems provide the ability to capture portions of a video source signal based upon a trigger. The trigger may be based upon an external event such as a user's input, or a signal from a separate test instrument. Alternatively, some systems provide for triggering based upon internally generated triggers. These internally generated triggers can be based upon a video source meeting certain desirable, or generally undesirable, characteristics, or other information included with the video source signal. For example, a trigger may be produced based upon a cyclical redundancy check (CRC) error, a gamut error, or ancillary data identification (ANC DID).
In some implementations, the raw video data is written into a circular buffer as it is received. In response to a trigger, the video data in the circular buffer is held to effectively capture the signal. The captured video data could consist of parts of a frame, a frame, a sequence of consecutive frames, a sequence of non-consecutive frames, or a combination thereof. The captured raw data is then available for additional analysis within the video test equipment. The captured raw data is not provided in a format that is readily used by other systems or applications.
Video test systems often use a video test generator to provide test patterns, including standard test patterns such as color bars. These test patterns are defined by a code format that can be used to generate a video frame for use in testing. The number and variety of test patterns from a video test generator may be numerous and yet still be limited to specific patterns based upon the nature of the test being conducted. These test patterns have not enabled problematic video sequences to be reproduced to allow for further testing of a video environment, such as a video production system.